Computer-based navigation systems for use on land have become available in a variety of forms and provide a variety of useful features. These types of navigation systems use databases that represent geographic features, such as roads, in a region. A navigation system can use the data to display maps for in-vehicle navigation, for example. The data used by a navigation system may provide a model of a road/street network with depth, accuracy and coverage to enable turn-by-turn route guidance, or to help a user find locations of specific restaurants, hotels, airports, and shopping centers, for example. Other useful features may include map display functions, vehicle positioning functions, and destination resolution capabilities, for example.
When performing a map display function with a navigation system, the sizes, shapes, and relative positions of geographic features in a portion of a geographic region are portrayed on a display associated with the navigation system. The geographic features being displayed may include roads, intersections, and points-of-interest, as well as other features, such as lakes, railroad tracks, buildings, airports, stadiums, parks, mountain ranges, docks, ferries, tunnels, and bridges, for example. To provide this map display function, geographic data includes information that allows the navigation system to display the size, shape, position, and character of these various geographic features on the display associated with the navigation system.
Traditional paper maps use different colors, different kinds of lines (e.g., solid, dashed, dotted, etc.) and lines of different widths to depict different geographic features and different types of certain geographic features. For example, paved roads may be depicted with solid lines and unpaved road may be depicted with dashed lines. Similarly, controlled access roads may be depicted with wide, red lines and narrow, low-volume residential roads may be depicted with thin, blue lines. Maps rendered graphically on computer displays using geographic data have generally followed these conventions. However, rendering maps graphically on a computer display with lines of different colors, shapes and widths to represent different kinds of geographic features can use a relatively significant amount of computing resources. Some computing devices used for displaying maps are portable systems (such as in-vehicle or hand-held systems) that have limited memory or processing resources. Thus, some computing systems that render maps graphically may limit the different kinds of lines, shapes and colors used to depict different geographic features.
Accordingly, it would be beneficial to provide an improvement for rendering maps on a display of a computing platform. Further, it would be beneficial to provide a computationally efficient means for rendering graphically on a computer display a map that includes a relatively wide palette of colors, widths and types of lines to represent different types of geographic features.